3,456 research outputs found
New determination of the D0→K -π +π0 and D0→K -π +π +π - coherence factors and average strong-phase d
No full textMeasurements of the coherence factors (RKππ0 and R K3π) and the average strong-phase differences (δDKππ0 and δDK3π) for the decays D0→K -π +π0 and D0→K -π +π +π - are presented. These parameters are important inputs to the determination of the unitarity triangle angle γ in B ∓→DK ∓ decays, where D designates a D0 or D-0 meson decaying to a common final state. The measurements are made using quantum correlated DD- decays collected by the CLEO-c experiment at the ψ(3770) resonance, and augment a previously published analysis by the inclusion of new events in which the signal decay is tagged by the mode D→KS0π+π- The measurements also benefit from improved knowledge of external inputs, namely the D0D-0 mixing parameters, rDKπ and several D-meson branching fractions. The measured values are RKππ0=0.82±0.07, δDKππ0=(164-14+20)°, RK3π=0.32-0.28+0.20 and δDK3π=(225-78+21)°. Consideration is given to how these measurements can be improved further by using the larger quantum-correlated data set collected by BESIII
Combined search for the Higgs boson with the D0 experiment
No full textWe perform a combination of searches for standard model Higgs boson production in collisions recorded by the D0 detector at the Fermilab Tevatron Collider at a center of mass energy of TeV. The different production and decay channels have been analyzed separately, with integrated luminosities of up to 9.7 fb and for Higgs boson masses GeV. We combine these final states to achieve optimal sensitivity to the production of the Higgs boson. We also interpret the combination in terms of models with a fourth generation of fermions, and models with suppressed Higgs boson couplings to fermions. The result excludes a standard model Higgs boson at 95% C.L. in the ranges $90 M_HM_
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New technologies in the D0 central tracker upgrade
No full textThe D0 collaboration has undertaken an aggressive upgrade of its central tracking system. The existing tracker will be completely removed and replaced by a two Tesla superconducting solenoidal magnet, an 837 000 channel silicon vertex system, and 80 000 channel scintillating fiber tracker, followed by a 7 680 channel central preshower detector and a 16 000 channel forward preshower detector. In this paper the author discusses all of the subsystems of the D0 central tracker upgrade, but will emphasize those aspects which involve new technology: radiation hard scintillating fiber, VLPC`s and extruded scintillating strips
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Top quark physics at the D0 experiment
No full textIn this paper I present the latest results on top quark physics from the D0 collaboration since the discovery of the top quark in March 1995. I summarize the discovery results, discuss progress since the discovery, and show how we can measure the top quark mass using three separate techniques. The measurements were made at the Fermilab Tevatron, a p{bar p} collider with {radical}s = TeV, using {approximately}50 pb{sup {minus}1} data collected from 1992 to early 1995
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Top physics at D0
No full textThe D0 collaboration reports on the observation of the Standard Model top quark in p{anti p} collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron. The authors have searched for t{anti t} production with an integrated luminosity of approximately 50 pb{sup {minus}1} in the dilepton and single-lepton decay channels, with and without tagging of b quark jets. They observe 17 events with an expected background of 3.8 {+-} 0.6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2 {times} 10{sup {minus}6} (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. They measure the top quark mass to be 199{sub {minus}21}{sup +19} (stat.) {sub {minus}21}{sup +14} (syst.) GeV/c{sup 2} and its production cross section to be 6.4 {+-} 2.2 pb. D0 also sees a hadronic W mass peak (W {yields} jj) in the t{bar t} data events. Preliminary results from multivariate analyses and from the t{bar t} data events. Preliminary results from multivariate analyses and from the t{bar t} {yields} all-jets channel are discussed. Preliminary determination of the top quark mass using dilepton events yields 145 {+-} 25 (stat.) {+-}20 (syst.) GeV/C{sup 2}
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SUSY Searches at D0
No full textSearches for evidence of supersymmetric particles, and other phenomena beyond the Standard Model, are well underway with the D0 detector at the Tevatron. The D0 detector has good central tracking, excellent energy and missing E{sub T} resolution, hermetic calorimetry, and wide muon coverage. Preliminary results from searches for gluino/squark production and first generation leptoquark production are presented, based on a small fraction of the data taken to date
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Electroweak physics from D0
No full textThe D0 detector was recently commissioned at the Tevatron p{bar p} collider and is presently taking data. Preliminary results from D0 are presented on properties of the W and Z electroweak gauge bosons, using final states containing electrons and muons
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The D0 Silicon Tracker: A completely redesigned vertex detector
No full textOver the last year and a half, the D0 collaboration has undertaken a complete redesign of the Silicon Tracker for its upgrade. The new design optimizes geometrical acceptance and tracking efficiency for {vert_bar}{eta}{vert_bar} {le} 2, in order to maximize the high transverse momentum physics accessible to D0 such as the top quark search. Details of the new design and reasons for the changes are presented here
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The D0 calorimeter trigger
No full textThe D0 calorimeter trigger system consists of many levels to make physics motivated trigger decisions. The Level-1 trigger uses hardware techniques to reduce the trigger rate from {approximately} 100kHz to 200Hz. It forms sums of electromagnetic and hadronic energy, globally and in towers, along with finding the missing transverse energy. A minimum energy is set on these energy sums to pass the event. The Level-2 trigger is a set of software filters, operating in a parallel-processing microvax farm which further reduces the trigger rate to a few Hertz. These filters will reject events which lack electron candidates, jet candidates, or missing transverse energy in the event. The performance of these triggers during the early running of the D0 detector will also be discussed
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The D0 Level 1.5 Calorimeter Trigger
No full textWe describe the design and preliminary performance of the D0 Level 1.5 Calorimeter Trigger
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